Diode laser irradiation system for biological tissue stimulation

ABSTRACT

A diode laser irradiation system for treating biological tissue of a subject without exposing the tissue to damaging thermal effects. The system includes a manipulable wand for contact with the tissue, a diode laser disposed in the wand for irradiating the tissue with coherent optical energy at a power output level of less than one thousand milliwatts, and laser setting controls for operating the diode laser to achieve a rate of absorption and conversion to heat in the irradiated tissue in a range between a minimum rate sufficient to elevate the average temperature of the irradiated tissue to a level above the basal body temperature of the subject, and a maximum rate which is less than the rate at which the irradiated tissue is converted into a collagenous.

CROSS REFERENCE TO RELATED APPLICATION

This is a continuation of U.S. Ser. No. 08/621,950, filed Mar. 25, 1996,U.S. Pat. No. 5,755,752, which is a continuation-in-part of U.S. Ser.No. 07/873,385, filed on Apr. 24, 1992, abandoned.

BACKGROUND OF THE INVENTION

The present invention relates generally to the treatment of livingbiological tissue by optical irradiation, and in particular to a systemfor stimulating soft, living tissue by diode laser irradiation.

Various non-surgical means have been employed in the therapeutictreatment of living tissue. Such techniques have included theapplication of ultrasonic energy, electrical stimulation, high frequencystimulation by diathermy, X-rays and microwave irradiation. While thesetechniques have shown some therapeutic benefit, their use has beensomewhat limited because they generate excessive thermal energy whichcan damage tissue. Consequently, the energy levels associated withtherapeutic treatments involving diathermy, X-ray, microwave andelectrical stimulation have been limited to such low levels that littleor no benefit has been obtained. Moreover, the dosage or exposure tomicrowaves and X-ray radiation must be carefully controlled to avoidcausing health problems related to the radiation they generate.Ultrasonic energy is non-preferentially absorbed and affects all of thetissue surrounding the area to which it is directed.

Optical energy generated by lasers has been used for various medical andsurgical purposes because laser light, as a result of its monochromaticand coherent nature, can be selectively absorbed by living tissue. Theabsorption of the optical energy from laser light depends upon certaincharacteristics of the wavelength of the light and properties of theirradiated tissue, including reflectivity, absorption coefficient,scattering coefficient, thermal conductivity, and thermal diffusionconstant. The reflectivity, absorption coefficient, and scatteringcoefficient are dependent upon the wavelength of the optical radiation.The absorption coefficient is known to depend upon such factors asinterband transition, free electron absorption, grid absorption (photonabsorption), and impurity absorption, which are also dependent upon thewavelength of the optical radiation.

In living tissue, water is a predominant component and has, in theinfrared portion of the electromagnetic spectrum, an absorption banddetermined by the vibration of water molecules. In the visible portionof the spectrum, there exists absorption due to the presence ofhemoglobin. Further, the scattering coefficient in living tissue is adominant factor.

Thus, for a given tissue type, the laser light may propagate through thetissue substantially unattenuated, or may be almost entirely absorbed.The extent to which the tissue is heated and ultimately destroyeddepends on the extent to which it absorbs the optical energy. It isgenerally preferred that the laser light be essentially transmissivethrough tissues which are not to be affected, and absorbed by tissueswhich are to be affected. For example, when applying laser radiation toa region of tissue permeated with water or blood, it is desired that theoptical energy not be absorbed by the water or blood, thereby permittingthe laser energy to be directed specifically to the tissue to betreated. Another advantage of laser treatment is that the optical energycan be delivered to the treatment tissues in a precise, well definedlocation and at predetermined, limited energy levels.

Ruby and argon lasers are known to emit optical energy in the visibleportion of the electromagnetic spectrum, and have been used successfullyin the field of ophthalmology to reattach retinas to the underlyingchoroidea and to treat glaucoma by perforating anterior portions of theeye to relieve interoccular pressure. The ruby laser energy has awavelength of 694 nanometers (nm) and is in the red portion of thevisible spectrum. The argon laser emits energy at 488 nm and 515 nm andthus appears in the blue-green portion of the visible spectrum. The rubyand argon laser beams are minimally absorbed by water, but are intenselyabsorbed by blood chromogen hemoglobin. Thus, the ruby and argon laserenergy is poorly absorbed by non-pigmented tissue such as the cornea,lens and vitreous humor of the eye, but is absorbed very well by thepigmented retina where it can then exert a thermal effect.

Another type of laser which has been adapted for surgical use is thecarbon dioxide (CO₂) gas laser which emits an optical beam which isabsorbed very well by water. The wavelength of the CO₂ laser is 10,600nm and therefore lies in the invisible, far infrared region of theelectromagnetic spectrum, and is absorbed independently of tissue colorby all soft tissues having a high water content. Thus, the CO₂ lasermakes an excellent surgical scalpel and vaporizer. Since it iscompletely absorbed, its depth of penetration is shallow and can beprecisely controlled with respect to the surface of the tissue beingtreated. The CO₂ laser is thus well-suited for use in various surgicalprocedures in which it is necessary to vaporize or coagulate neutraltissue with minimal thermal damage to nearby tissues.

Another laser in widespread use is the neodymium dopedyttrium-aluminum-garnet (Nd:YAG) laser. The Nd:YAG laser has apredominant mode of operation at a wavelength of 1064 nm in the nearinfrared region of the electromagnetic spectrum. The Nd:YAG opticalemission is absorbed to a greater extent by blood than by water makingit useful for coagulating large, bleeding vessels. The Nd:YAG laser hasbeen transmitted through endoscopes for treatment of a variety ofgastrointestinal bleeding lesions, such as esophageal varices, pepticulcers, and arteriovenous anomalies.

The foregoing applications of laser energy are thus well-suited for useas a surgical scalpel and in situations where high energy thermaleffects are desired, such as tissue vaporization, tissue cauterization,and coagulation.

Although the foregoing laser systems perform well, they commonlygenerate large quantities of heat and require a number of lenses andmirrors to properly direct the laser light and, accordingly, arerelatively large, unwieldy, and expensive. These problems are somewhatalleviated in some systems by locating a source of laser light distalfrom a region of tissue to be treated and providing fiber optic cablefor carrying light generated from the source to the tissue region,thereby obviating the need for a laser light source proximal to thetissue region. Such systems, however, are still relatively large andunwieldy and, furthermore, are much more expensive to manufacture than asystem which does not utilize fiber optic cable. Moreover, the foregoingsystems generate thermal effects which can damage living tissue, ratherthen provide therapeutic treatment to the tissue.

Therefore, what is needed is a system and method for economicallystimulating soft, living tissue with laser energy without damaging thetissue from the thermal effects of the laser energy.

SUMMARY OF THE INVENTION

The present invention, accordingly, provides a system and a method thatretains all of the advantages of the foregoing systems while reducingthe size and cost of the system. To this end, a system for treatingbiological tissue without exposing the tissue to damaging thermaleffects, comprises a wand which houses an Indium Gallium Arsenide(In:GaAs) diode laser configured for generating coherent optical energyradiation having a wavelength in the range of the near infrared regionof the electromagnetic spectrum at a power output in the range of fromabout 100 milliwatts (mw) to about 1000 mw. The coherent optical energyradiation is focused on the treatment area to achieve a rate ofabsorption and conversion to heat in the irradiated tissue in the rangebetween a minimum rate sufficient to elevate the average temperature ofthe irradiated tissue to a level above the basal body temperature of theliving subject, and a maximum rate which is less than the rate at whichthe irradiated tissue is converted into a collagenous substance.

In another aspect of the present invention, the amount of Indium withwhich the Gallium Arsenide in the diode is doped is appropriate to causethe wavelength of laser light generated by the diode to be in a rangebetween 1064±20 nm and 2500±20 nm.

The system and method additionally enable the treatment time, the powergenerated by the laser, and the mode of operation (pulsed or continuouswattage (CW)) to be carefully controlled by an operator according to adesired treatment protocol.

An advantage achieved with the present invention is that it enableslaser light to be safely and effectively applied to a region of livingtissue for therapeutic purposes, for example, to reduce pain, reduceinflammation, and enhance the healing of tissue by stimulation ofmicrocirculation, without exposing the tissue to damaging thermaleffects.

Another advantage of the present invention is that, because the laserlight is generated within the wand, it is less expensive to manufacturethan systems utilizing fiber optic cables.

Another advantage of the present invention is that it provides for highpower dissipation levels ranging from about 500 milliwatts (mw) to about1000 mw in both continuous wattage (CW) or pulsed modes of operation.The diode laser system enables such high power dissipation levels to beachieved utilizing a portable, battery operated arrangement.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic diagram of a diode laser irradiation system ofthe present invention.

FIG. 2 shows an elevational view of a wand used in the system of FIG.

FIG. 3A shows an enlarged, elevational view of a laser resonator used inthe wand of FIG. 2.

FIG. 3B shows an enlarged, end view of the laser resonator used in thewand of FIG. 3A.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1, the reference numeral 10 refers generally to thediode laser irradiation system of the present invention which includes abiostimulation control unit 12 for controlling the operation of ahand-operated probe, i.e., a laser treatment wand 14, electricallyconnected to the control unit via a coaxial cable 16. As will bedescribed in detail below, the wand 14 houses a diode laser capable ofemitting low level reactive laser light for use in tissue irradiationtherapy.

The control unit 12 receives power through a power supply line 18adapted for connection to a conventional 120-volt power outlet. A groundpiece 19 is connected to the control unit 12 and is held by a patientreceiving the tissue irradiation therapy to provide an electrical groundfor safety purposes. An on/off switch 20 is connected in series with theline 18 for controlling the flow of power through the line. A foot pedal22 is connected to the control unit 12 and is depressible for activatingthe generation and emission of laser light from the wand 14. Activationmay alternatively, or additionally, be provided using a switch on thewand 14.

The control unit 12 includes laser setting controls 24 and correspondingsetting displays 26. The setting controls 24 are utilized to selectoperational parameters of the control unit 12 to effect the rate ofabsorption and conversion to heat of tissue irradiated by the wand 14,according to desired treatment protocols. Generally, the treatmentprotocols provide for a rate of absorption and conversion to heat in theirradiated tissue in a range between a minimum rate sufficient toelevate the average temperature of the irradiated tissue to a levelabove the basal body temperature of the subject and a maximum rate whichis less than the rate at which the irradiated tissue is converted to acollagenous substance. The treatment protocols vary time, power, andpulse/continuous mode parameters in order to achieve the desiredtherapeutic effects.

The setting controls 24 include a treatment time control 28, a powercontrol 30, and a pulse/continuous mode control 32. Adjustments intreatment time, power and pulse/continuous mode operation of the wand 14utilizing the controls 28-32 make possible improved therapeutic effectsbased upon the aforementioned treatment protocols involving one or moreof these parameters. Also, an impedance control 34 is provided adjustingan impedance measurment of the tissue to a baseline value, according toskin resistance, as discussed further below, whereby improvements intissue condition may be monitored. It is understood that, according tothe specific embodiment of the control unit 12, the setting controls 24may include any combination of one or more of the controls 28-34.

The setting displays 26 include a time display 36, a power display 38, apulse display 40 and an impedance display 42. In one embodiment, each ofthe displays 26 are light emitting diode (LED) displays such that thecorresponding setting controls 24 can be operated to increment ordecrement the settings, which are then indicated on the displays. Aprogrammed settings control 44 is used to save setting selections andthen automatically recall them for convenience, using one or morebuttons 44a-44c, for example.

The time control 28 adjusts the time that laser light is emitted fromthe wand 14 from 0.01 to 9.99 minutes in 0.01 minute intervals, asindicated on the time display 36. The time display 36 includes acountdown display 36a and an accumulated display 36b. Once the timecontrol 28 is set, the countdown display 36a indicates the setting sothat as the wand 14 is operated the time is decremented to zero. Theaccumulated time display 36b increments from zero (or any other resetvalue) as the wand 14 is operated so that the total treatment time isdisplayed. The time display 36 takes into account the pulsed orcontinuous mode operation of the system 10.

The power control 30 adjusts the power dissipation level of the laserlight from the wand 14 in a range from zero to 1000 mw, with typicaloperation ranging from about 500 mw to 1000 mw. The pulse/continuousmode control 32 sets the system 10 to generate laser light energy fromthe wand 14 either continuously or as a series of pulses. The control 32may include, for example, a pulse duration rheostat (not shown) foradjusting the pulse-on or pulse-off time of the wand 14. In oneimplementation, the pulses-per-second (PPS) is set in a range from zeroto 9995, adjustable in 5 step increments. The PPS setting is displayedon a PPS display 40a. The pulse duration may alternatively, oradditionally, be displayed indicating the duty cycle of pulses rangingfrom 5 to 99 (e.g., 5 meaning that the laser is "on" 5% of the time). Acontinous mode display 40b is activated when the system 10 is beingoperated in the continuous wattage (CW) mode of operation.

An audio volume control 46 is provided for generating an audible warningtone from a speaker 48 when laser light is being generated. Thus, forexample, the tone may be pulsed when the system is operating in thepulse mode of operation.

The impedance control 34 is a sensitivity setting that is calibrated andset, according to the tissue skin resistance, to a baseline value whichis then indicated on the impedance display 42. As therapy progresses theimpedance readout on the display 42 changes (i.e., it decreases) therebyindicating progress of treatment.

A calibration port 49 is utilized to verify laser performance by placingthe wand 14 in front of the port and operating the system 10. The port49 determines whether the system 10 is operating within calibrationspecifications and automatically adjusts the system parameters.

While not shown, the control unit 12 includes digital and analogelectronic circuitry for implementing the foregoing features. Thedetails of the electronic circuitry necessary to implement thesefeatures will be readily understood by one of ordinary skill in the artin conjunction with the present disclosure and therefore will not bedescribed in further detail.

Referring to FIG. 2, the wand 14, sized to be easily manipulated by theuser, includes a heat-conductive, metal bar 50. The bar 50 is hollowalong its central axis and is threaded on its interior at a first endfor receiving a laser resonator 52, described further below withreference to FIGS. 3A and 3B. Wiring 51 extends from the resonator 52through the hollow axis of the bar 50 for connection to the coaxialcable 16 (FIG. 1). In the preferred embodiment the bar 50 is copper orsteel and thus conducts electricity for providing a ground connectionfor the resonator 52 to the cable 16.

A glass noryl sleeve 54 is placed over the bar 50 for purposes ofelectrical and thermal insulation. A screw 55 extending through thesleeve 54 anchors the sleeve to the bar 50. As shown, the resonator 52is recessed slightly within the sleeve 54. An impedance oring 56, formedof a conductive metal, is press-fitted into the end of the sleeve 54 sothat when the wand 14 makes contact with tissue, the ring 56 touches thetissue. The ring 56 is electrically connected through the wand 14 to theunit 12. The ring 56 measures impedance by measuring angular DCresistance with an insulator ohmmeter, for example, of the tissue beingirradiated by the wand 14 which is then displayed as impedance on thedisplay 42. Any other suitable impedance measurement circuit may beutilized, as will be apparent to one skilled in the art. Measurements ofimpedance are useful in therapy to determine whether healing hasoccurred. For example, a baseline measurement of impedance provides anobjective value of comparison wherein as the tissue heals, a lowerimpedance approaching the baseline is observed. The impedance value readcan also be used to determine the amount of milliwattage and time oftreatment appropriate for the patient.

A feedback sensor 57 is located in the end of the sleeve 54 formeasuring the output of the resonator 52. While not shown, the sensor 57is connected electronically to the control unit 12 and to a feedbackcircuit within the control unit. A small percentage of the diode laserlight from the resonator 52 is thus detected by the sensor 57 andchanneled into the feedback circuit of the control unit 12 to measureand control performance of the resonator. Out-of-specificationtemperature, power, pulse frequency or duration is thus corrected or thesystem 10 is automatically turned off.

Multiple metallic fins 58 are placed over the end of the bar 50 and areseparated and held in place by spacers 60 press-fitted over the bar 50.The fins 58 act as a heat sink to absorb heat from the laser through thebar 50 and dissipate it into the surrounding air. The spacers 60 placedbetween each fin 58 enable air to flow between the fins, therebyproviding for increased heat transfer from the wand 14.

A casing 62 fits over the sleeve 54 and serves as a hand grip andstructure to support a switch 64 and light 66. The switch 64 is used toactuate the wand 14 by the operator wherein the switch must be depressedfor the wand to operate. The switch 64 is wired in a suitable manner tothe control unit 12 and is used either alone or in conjunction with thefoot pedal 22. The light 66 is illuminated when the wand 14 is inoperation.

As shown in FIG. 3A, the laser resonator 52 includes a housing 68 havingthreads 68a configured for matingly engaging the threaded portion of thebar 50 in its first end. An Indium-doped Gallium Arsenide (In:GaAs)semiconductor diode 70 is centrally positioned in the housing 68 facingin a direction outwardly from the housing 68, and is electricallyconnected for receiving electric current through the threads 68a and anelectrode 72 connected to the wiring 51 that extends longitudinallythrough the hollow interior of the tube 50 (FIG. 2). The amount ofIndium with which the Gallium Arsenide is doped in the diode 70 is anamount appropriate so that the diode 70, when electrically activated,generates, in the direction outwardly from the housing 68, low levelreactive laser light having, at a power output level of 100-1000 mw, afundamental wavelength ranging from, depending upon the implementation,about 1064±20 nm to 2500±20 nm in the near-infrared region of theelectromagnetic spectrum. Other types of diode semiconductor lasers mayalso be used to produce the foregoing wavelengths, e.g., Helium Neon,GaAs or the like.

As shown in FIGS. 3A and 3B, a lens 74 is positioned at one end of thehousing 68 in the path of the generated laser light for focusing thelight onto tissue treatment areas of, for example, 0.5 mm² to 2 mm², andto produce in the treatment areas an energy density in the range of fromabout 0.01 to about 0.15 joules/mm². The lens 74 may be adjusted todetermine depth and area of absorption.

The operating characteristics of the diode 70 are an output power levelof 100-1000 mw, a center fundamental wavelength of 1064±20 nm to 2500±20nm, with a spectral width of about 5 nm, a forward current of about 1500milliamps, and a forward voltage of about 5 volts at the maximumcurrent.

In operation, the switch 20 is closed (i.e., turned on) to power up thecontrol unit 12, at which time the displays becomes illuminated, therebyindicating that the control unit is receiving power. The time control 28is set for specifying a desired duration of time for laser treatment,which time is displayed on the countdown display 36a. The mode control34 is set for specifying whether the laser light is to be generated inthe continuous or the pulsed mode. If the pulsed mode is selected, thenthe duration of the pulse on-time/off-time is specified and thepulses-per-second (and the pulse duty cycle if appropriate) is displayedon the PPS display 40a. If the continuous mode instead is chosen, thecontinuous mode display 40b is illuminated. It can be appreciated thatthe mode and the pulse time-on and time-off settings affect theintensity of the treatment provided. The amount of power is further setby the power control 30, and displayed on the power display 38. It canbe appreciated that the power, duration and pulse intensity of treatmentis is thus selectable by the unit 12 and is to be determined bytreatment protocols relating to the character of the tissue to betreated, the depth of penetration desired, the acuteness of the injury,and the condition of the patient. The audio volume control 46 can beadjusted to control the volume of the tone generated from the speaker48. The tissue impedance display 42 indicates an impedance value fortissue in contact with it and can be calibrated to a baseline set forthe patient by applying the wand 14 to surrounding non-damaged tissueand then when the wand 14 is applied to the damaged tissue, an impedancevalue (much higher than the baseline) will be indicated and hopefullyreduced over time, through treatment, to the baseline value.

After the time, power, and mode (continuous wattage or pulsed at aselected intensity) selections are made, the wand 14 may be directedinto the calibration port 49 to verify the accuracy of the system. Thewand 14 may then be applied to patient tissue for therapy, The footpedal 22 and/or the switch 64 may be depressed to cause therapeuticlaser light energy to be generated from the wand 14. As an indication ofthat laser light energy is being generated, an audible tone is generatedfrom the speaker 32. In accordance with the foregoing specification ofthe laser diode 70, the laser light energy is generated at a fundamentalwavelength of 1064 nm at an output power level of from about 100-800 mw.In other implementations the laser light wavelength may be as high asabout 2500 nm and power of up to 1000 mw.

The generated laser optical energy is applied to regions of the bodywhere decreased muscle spasms, increased circulation, decreased pain, orenhanced tissue healing is desired. The surface of the tissue in theregion to be treated is demarcated to define an array of grid treatmentpoints, each of which points identifies the location of anaforementioned small treatment area. Each small treatment area isirradiated with the laser beam light to produce the desired therapeuticeffect. Because laser light is coherent, a variable energy density ofthe light of from about 0.01 to 0.15 joules/mm² is obtained as the lightpasses through the lens 74 and converges onto each of the smalltreatment areas. The energy of the optical radiation is controlled bythe power control 30 and applied (for durations such as 1 minute to 3minutes, continuous wattage or pulsed, for example) as determined bytreatment protocols, to cause the amount of optical energy absorbed andconverted to heat to be within a range bounded by a minimum absorptionrate sufficient to elevate the average temperature of the irradiatedtissue to a level which is above the basal body temperature, but whichis less than the absorption rate at which tissue is converted into acollagenous substance. The laser beam wavelength, spot or beam size,power dissipation level, and time exposure are thus carefully controlledto produce in the irradiated tissue a noticeable warming effect which isalso limited to avoid damaging the tissue from thermal effects.

The present invention has several advantages. For example, by using anIn:GaAs diode laser to generate the laser beam energy, the laser sourcecan be made sufficiently small to fit within the hand-held wand 14,thereby obviating the need for a larger, more expensive laser source andthe fiber optic cable necessary to carry the laser energy to thetreatment tissue. The In:GaAs diode laser can also produce greater laserenergy at a higher power dissipation level than lasers of comparablesize. Furthermore, construction of the wand 14 including the fins 58provides for the dissipation from the wand of the heat generated by thelaser source.

A further advantage is that therapeutic treatment by the foregoing lowlevel reactive laser system has been shown to reduce pain in softtissue, reduce inflammation, and enhance healing of damaged tissue bythe stimulation of microcirculation, without subjecting the livingtissue to damaging thermal effects. This phenomenon is due to certainphysiological mechanisms in the tissue and at the cellular level thatoccur when the above process is used. In the evaluation of themicrocirculatory system, for example, it has been demonstrated that theblood vessel walls possess photosensitivity. When the blood vessel wallsare exposed to laser irradiation as set forth above, the tonus isinhibited in smooth myocytes, thus increasing the blood flow in thecapillaries. Other effects which have been observed are: peripheralcapillaries neovascularization, reduction of blood platelet aggregation,reduction of O₂ from the triplet to the singlet form which allows forgreater oxygenation of the tissue, reduction of buffer substanceconcentration in the blood, stabilization of the indices of erythrocytedeformation, reduction of products of perioxidized lipid oxygenation ofthe blood. Other effects which have been observed are increased index ofantithrombin activity, stimulation of the enzymes of the antioxidantsystem such as superoxide dismutase and catalase. An increase in thevenous and lymph and outflow from the irradiated region has beenobserved. The tissue permeability in the area is substantially enhanced.This assists in the immediate reduction of edema and hematomaconcentrations in the tissue. At the cellular level, the mitochondriahave also been noted to produce increased amounts of ADP with subsequentincrease in ATP. There also appears to be an increased stimulation ofthe calcium and sodium pumps at the tissue membrane at the cellularlevel.

At the neuronal level, the following effects have been observed as aresult of the foregoing therapeutic treatment. First, there is anincreased action potential of crushed and intact nerves. The bloodsupply and the number of axons is increased in the irradiated area.Inhibition of scar tissue is noticed when tissue is lazed. There is animmediate increase in the membrane permeability of the nerve. Long termchanges in the permeability of calcium and potassium ions through thenerve for at least 120 days have been observed. The RNA and subsequentDNA production is enhanced. Singlet O₂ is produced which is an importantfactor in cell regeneration. Pathological degeneration with nerve injuryis changed to regeneration. Both astrocytes and oligodedrocytes arestimulated which causes an increased production of peripheral nerveaxons and myelin.

Phagocytosis of the blood cells is increased, thereby substantiallyreducing infection. There also appears to be a significantanti-inflammatory phenomena which provides a decrease in theinflammation of tendons, nerves, bursae in the joints, while at the sametime yielding a strengthening of collagen. There is also an effect onthe significant increase of granulation tissue in the closure of openwounds under limited circulation conditions.

Analgesia of the tissue has been observed in connection with a complexseries of actions at the tissue level. At the local level, there is areduction of inflammation, causing a reabsorption of exudates.Enkephalins and endorphins are recruited to modulate the pain productionboth at the spinal cord level and in the brain. The serotnogenic pathwayis also recruited. While it is not completely understood, it is believedthat the irradiation of the tissue causes the return of an energybalance at the cellular level which is the reason for the reduction ofpain.

It is understood that several variations may be made in the foregoingwithout departing from the scope of the invention. For example, anynumber of fins 58 may be utilized as long they dissipate sufficient heatfrom the wand 14 so that the user may manipulate the wand withoutgetting burned. The setting controls 24 may be used individually or incombination and the information displayed on the displays 26 may vary.Other diode laser structures may be utilized to produce the desiredeffects.

Although illustrative embodiments of the invention have been shown anddescribed, a wide range of modification, change, and substitution iscontemplated in the foregoing disclosure and in some instances, somefeatures of the present invention may be employed without acorresponding use of the other features. Accordingly, it is appropriatethat the appended claims be construed broadly and in a manner consistentwith the scope of the invention.

What is claimed is:
 1. A diode laser cooling apparatus for cooling adiode laser used in a diode laser irradiation system for treatingbiological tissue of a subject without exposing the tissue to damagingthermal effects, the apparatus comprising:a conductive bar forsupporting the diode laser at one end thereof; an insulative sleeve overthe bar; and a plurality of cooling fins connected to an opposite end ofthe bar for transferring heat generated by the diode laser to thesurrounding air.
 2. A manipulable wand for use in a diode laserirradiation system for treating biological tissue of a subject withoutexposing the tissue to damaging thermal effects, comprising:a diodelaser for irradiating the tissue with coherent optical energy at apredetermined power output level focused to an area in the range ofabout 0.5 mm² to about 2 mm² ; a conductive bar for supporting the diodelaser at one end thereof; an insulative sleeve over the bar; and acooling fin connected to the bar for transferring heat generated by thediode laser to the surrounding air.
 3. The wand of claim 2 wherein thepredetermined power output level is less than one thousand milliwatts.